What is a Stem Wall?

The construction of the stem wall is one of the first and most important steps in building a structure. It is an integral part of the property as it relates to how the foundation and the walls meet, and it keeps the structure stable. If a stem wall has not been properly constructed, a building may be at risk of being unsafe as a result of movement. Here's some information to give you a better understanding of what a stem wall is and why it is so important.

Construction

Whether it is a residential or commercial building that is to be erected, the foundation is the base of the building and is the first thing to be laid. It is completed and in place before the construction of the stem wall is considered.

This makes up the footprint of the building, and the stem wall will be constructed around it. A trench is excavated around the foundation for the construction of the stem wall.

There are several stages to the construction of a stem wall, which begins with cinder blocks that are reinforced with steel rods and concrete.

Depending on the building, the stem wall is usually built to the height of three cinder blocks. Each row of cinder blocks is laid in turn before the concrete is poured. This is done at the same time as the concrete slab that tops the foundation. The process is completed in one go so that there is no separation between the foundation and the stem wall.

Once the stem wall is in place, gravel is packed on either side of the base of the lowest row which prevents the growth of vegetation.

Purpose

The stem wall is, effectively, part of the foundation. Though not the part of the building that is underfoot — what we would normally consider the only foundation — it anchors the foundation to the ground.

A building is strengthened by a well-constructed stem wall, partially due to the fact that the concrete is poured in one continuous action. The lack of seam in the concrete keeps it strong and prevents water from entering and weakening the structure.

The stem wall is to a building what roots are to plants in terms of keeping them tied to the ground. A building without an adequate stem wall would be like attempting to plant a cut flower in the earth: there would be no stability.

Benefits

The main benefit of a stem wall is that it helps to prevent structural damage. In areas prone to floods and storms, a building is more likely to remain structurally sound where the water moves around the structure rather than penetrating it. Water can cause the foundation to lift which makes the building more susceptible to strong winds, resulting in movement, cracking, and gradual sinking.

The structural integrity of a building is maintained by a good foundation, the stem wall being a major part of this system that holds a building in place.